From 11b247918e97bf8c47875d630f9b46128fe29015 Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Fri, 9 Feb 2024 11:35:40 +0900
Subject: [PATCH] [qfcc] Find current algebra context for duals

Now finding the dual of a scalar works, too (need a context as otherwise
the pseudo-scalar is unknown).
---
 tools/qfcc/include/algebra.h     |  1 +
 tools/qfcc/source/algebra.c      | 20 ++++++++++++++++++++
 tools/qfcc/source/expr_algebra.c |  5 ++---
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/tools/qfcc/include/algebra.h b/tools/qfcc/include/algebra.h
index b40c77bd7..152f58234 100644
--- a/tools/qfcc/include/algebra.h
+++ b/tools/qfcc/include/algebra.h
@@ -94,6 +94,7 @@ type_t *algebra_mvec_type (algebra_t *algebra, pr_uint_t group_mask);
 int algebra_count_flips (const algebra_t *alg, pr_uint_t a, pr_uint_t b) __attribute__((pure));
 struct ex_value_s *algebra_blade_value (algebra_t *alg, const char *name);
 struct symtab_s *algebra_scope (type_t *type, struct symtab_s *curscope);
+algebra_t *algebra_context (const type_t *type) __attribute__((pure));
 void algebra_print_type_str (struct dstring_s *str, const type_t *type);
 void algebra_encode_type (struct dstring_s *encoding, const type_t *type);
 int algebra_type_size (const type_t *type) __attribute__((pure));
diff --git a/tools/qfcc/source/algebra.c b/tools/qfcc/source/algebra.c
index efbe97cad..d4b1930ba 100644
--- a/tools/qfcc/source/algebra.c
+++ b/tools/qfcc/source/algebra.c
@@ -42,6 +42,7 @@
 #include "tools/qfcc/include/attribute.h"
 #include "tools/qfcc/include/diagnostic.h"
 #include "tools/qfcc/include/expr.h"
+#include "tools/qfcc/include/shared.h"
 #include "tools/qfcc/include/strpool.h"
 #include "tools/qfcc/include/struct.h"
 #include "tools/qfcc/include/symtab.h"
@@ -675,6 +676,25 @@ algebra_get (const type_t *type)
 	}
 }
 
+algebra_t *
+algebra_context (const type_t *type)
+{
+	algebra_t *alg = nullptr;
+	if (type && is_algebra (type)) {
+		alg = algebra_get (type);
+	}
+	if (!alg) {
+		symtab_t   *scope = current_symtab;
+		while (scope && scope->procsymbol != algebra_symbol) {
+			scope = scope->parent;
+		}
+		if (scope) {
+			alg = scope->procsymbol_data;
+		}
+	}
+	return alg;
+}
+
 void
 algebra_print_type_str (dstring_t *str, const type_t *type)
 {
diff --git a/tools/qfcc/source/expr_algebra.c b/tools/qfcc/source/expr_algebra.c
index b2ddd66cf..515c14fe8 100644
--- a/tools/qfcc/source/expr_algebra.c
+++ b/tools/qfcc/source/expr_algebra.c
@@ -2708,11 +2708,10 @@ algebra_negate (const expr_t *e)
 const expr_t *
 algebra_dual (const expr_t *e)
 {
-	if (!is_algebra (get_type (e))) {
-		//FIXME check for being in an @algebra { } block
+	auto algebra = algebra_context (get_type (e));
+	if (!algebra) {
 		return error (e, "cannot take the dual of a scalar without context");
 	}
-	auto algebra = algebra_get (get_type (e));
 	auto layout = &algebra->layout;
 
 	const expr_t *a[layout->count] = {};